_Warwick._ There is a history in all men's lives, Figuring the nature of the times deceased; The which observed, a man may prophesy, With a near aim, of the main chance of things As yet not come to life, which in their seeds, And weak beginnings, lie intreasured. Such things become the hatch and brood of time; And, by the necessary form of this, King Richard might create a perfect guess, That great Northumberland, then false to him, Would, of that seed, grow to a greater falseness, Which should not find a ground to root upon, Unless on you. _King Henry._ Are these things, then, necessities? _King Henry IV._ Part II. Act. 3, Sc. I. When equally competent thinkers appear to take directly opposite views of a matter of purely speculative interest, it will commonly be found that their differences arise from their using the same words in different senses, or from their being, by some other cause, prevented from thoroughly apprehending each other's meaning. An illustration is afforded by the controversy regarding the possibility of constructing a Science of History, which could scarcely have been so much prolonged if all who have taken part in it had begun by defining their terms, had agreed to and adhered to the same definitions, and had always kept steadily in view the points really in debate. If the word 'science' had been used only in the restricted, though rather inaccurate sense in which it is sometimes employed by some of the most distinguished of the disputants, there would have been less question as to its applicability to history. No one doubts that from an extensive historical survey may be drawn large general deductions on which reasonable expectations may be founded. No one denies that the experience of the past may teach lessons of political wisdom for the guidance of the future. If it were not so, history would be as uninstructive as fairy lore; its chief use would be to amuse the fancy; and little more practical advantage could result from investigating the causes of the failure of James II.'s designs on civil and religious liberty, than from an inquiry into the artifices by which Jack-the-Giant-killer contrived to escape the maw of the monsters against whom he had pitted himself. What is commonly understood, however, by a Science of History is something far beyond the idea entertained of it by such temperate reasoners as Mr. John Stuart Mill and Mr. Fitzjames Stephen. The science, for the reality of which M. Comte in France and Mr. Buckle in England have been the foremost champions, would bear the same relation to political events as Optics and Astronomy do to the phenomena of light and of the solar and sidereal systems. It would deal less with the conjectural and probable than with the predicable and positive. 'In the moral as in the physical world,' say its leading advocates, 'are invariable rule, inevitable sequence, undeviating regularity,' constituting 'one vast scheme of universal